Chemistry Term Paper - Copy
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Transcript of Chemistry Term Paper - Copy
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My topic SOLAR ENERGY is all about the ever
evolving technologies which has been harnessed
by humans since ancient times as radiant light,heat from sun etc. for the generation of
electricity using these solar energies. Solar
radiation along with secondary powered
resources such as wind and wave power,
hydroelectricity and biomass, accounts for mostof the available renewable energy on the earth.
Only a minuscule fraction of the available solar
energy is used.
Solar technologies are
broadly characterized as either Passive solar orActive solar depending on the way they capture,
convert and distribute solar energy. Active solar
techniques include the use of photovoltaic panels
and solar thermal collectors to harness the
energy. Passive solar techniques include
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orienting a building to the Sun, selecting
materials with favourable thermal mass or light
dispersing properties, and designing spaces thatnaturally circulate air.
Solar energy in terms of
thermal Solar Hot Water systems and electricity
producing Photovoltaic contribute at present only
to the global energy supply at a fraction of 1 %.
However, the potential for solar energy is
immense: the earth receives in 1 hour from the
sun the equivalent of the present annual global
energy supply.
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Solar energy is one of the emerging
renewable energy technologies still not
competitive, but exhibiting both technical andeconomic potential to be so inside 10-15 years.
There is basically no necessary technology
jumps as prerequisites, but such a development
will demand a favourable political climate.
Growing political awareness, driven partly byenvironmental concerns partly by concerns about
security of energy supply, of the need to promote
solar energy and renewables, e.g. on global level
spurred on by the recent UN/IPCC report and on
an EU level by the EC commitment to reach 20% renewables in the electricity supply by 2010
and 20 % renewables in the overall energy
production by 2020, appears to ensure the
necessary future political support for renewables,
but not necessarily for solar energy technologies,
in particular photovoltaic, which is still not yet
competitive to other renewables although
exhibiting a tremendous potential.
The contents of the topic Solar
energy is as follow:
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A: Energy from the sun.
B: Introduction.
C: Applications of solar technologies:
i) Solar lightning.
ii) Solar thermals.
iii) Solar vehicles.
D: Energy storage methods.
E: Development, Deployment and Economics.
F: ISO Standards
G: Notes and conclusions.H: References.
The Earth receives
174 petawatts (PW) of incoming solar radiation
(insolation) at the upper atmosphere.
Approximately 30% is reflected back to space
while the rest is absorbed by clouds, oceans and
land masses. The spectrum of solar light at the
Earth's surface is mostly spread across the visible
and near-infrared ranges with a small part in the
near-ultraviolet.
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Earth's land surface, oceans
and atmosphere absorb solar radiation, and this
raises their temperature. Warm air containingevaporated water from the oceans rises, causing
atmospheric circulation or convection. When the
air reaches a high altitude, where the
temperature is low, water vapour condenses into
clouds, which rain onto the Earth's surface,completing the water cycle. The latent heat of
water condensation amplifies convection,
producing atmospheric phenomena such as
wind, cyclones and anti-cyclones. Sunlight
absorbed by the oceans and land masses keepsthe surface at an average temperature of 14 C.
By photosynthesis green plants convert solar
energy into chemical energy, which produces
food, wood and the biomass from which fossil
fuels are derived.
The potential for solar
energy is very high about one hour sunshine
on the surface of the earth corresponds to the
present annual global energy consumption.
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However renewable and solar energy still plays a
very minor role in the global energy supply.
Although the contribution of solar energy to theglobal energy supply is quite small at present,
less than 0,05 percent, the growth rate of solar
energy has been relatively high, albeit from a
very low starting point.
In the period 1971 to 2004 exhibited an annual
growth rate of 2, 3 percent, almost on par with
the growth rate of the global energy supply,
whereas solar energy in the same period grew by
almost 30 % per year in average with higher
growth rates in the recent years.
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Solar energy refers
primarily to the use of solar radiation forpractical ends. However, all renewable energies,
other than geothermal and tidal, derive their
energy from the sun.
Solar technologies are broadly
characterized as either passive or active
depending on the way they capture, convert and
distribute sunlight. Active solar techniques use
photovoltaic panels, pumps, and fans to convert
sunlight into useful outputs. Passive solar
techniques include selecting materials with
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favourable thermal properties, designing spaces
that naturally circulate air, and referencing the
position of a building to the Sun. Active solartechnologies increase the supply of energy and
are considered supply side technologies, while
passive solar technologies reduce the need for
alternate resources and are generally considered
demand side technologies.
Day lighting systems
collect and distribute sunlight to provide interior
illumination. This passive technology directly
offsets energy use by replacing artificial lighting,
and indirectly offsets non-solar energy use by
reducing the need for air-conditioning. Although
difficult to quantify, the use of natural lighting
also offers physiological and psychological
benefits compared to artificial lighting. Day
lighting design implies careful selection ofwindow types, sizes and orientation; exterior
shading devices may be considered as well.
Individual features include saw tooth roofs,
clerestory windows, light shelves, skylights and
light tubes. When day lighting features are
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properly implemented they can reduce lighting-
related energy requirements by 25%.
Solar thermal technologies
can be used for water heating, space cooling,
space heating and process heat generation. In
Solar thermal we includes:
Water Heating: In this we use solar energy to
heat up the water.The most common types ofsolar water heaters are evacuated tube collectors
(44%) and glazed flat plate collectors (34%)
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generally used for domestic hot water and
unglazed plastic collectors (21%) used mainly to
heat swimming pools.
Heating, cooling and ventilation:Solar heating,cooling and ventilation technologies can be used
to offset a portion of this energy.
Water Treatment: Solar energy may be used in a
water stabilisation pond to treat waste water
without chemicals or electricity. A further
environmental advantage is that algae grow in
such ponds and consume carbon dioxide in
photosynthesis, although algae may produce
toxic chemicals that make the water unusable.
Cooking: Solar cookers use sunlight for cooking,
drying and pasteurization. They can be grouped
into three broad categories: box cookers, panel
cookers and reflector cookers. The simplest solar
cooker is the box cooker first built by Horace de
Saussure in 1767. A basic box cooker consists of
an insulated container with a transparent lid. It
can be used effectively with partially overcast
skies and will typically reach temperatures of 90
150 C. Panel cookers use a reflective panel to
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direct sunlight onto an insulated container and
reach temperatures comparable to box cookers.
Reflector cookers use various concentratinggeometries to focus light on a cooking container.
These cookers reach temperatures of 315 C and
above but require direct light to function properly
and must be repositioned to track the Sun.
Development of solar
powered car has been an engineering goal since
1980. The world solar challenge is biannual
solar powered car race, where teams from
universities and enterprises compete over 3,021
kilometers across central Australia from Darwin
to Adelaide.
Solar powered car
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1) Solar
energy is not available at night, and energy
storage is an important issue because modernenergy systems usually assume continuous
availability of energy.
2) Thermal mass systems can store solar energy
in the form of heat at domestically useful
temperatures for daily or seasonal durations.
3) Thermal storage systems generally use readily
available materials with high specific heat
capacities such as water, earth and stone.
4) Well-designed systems can lower peakdemand, shift time-of-use to off-peak hours and
reduce overall heating and cooling requirements.
5) Phase change materials such as paraffin wax
and Glauber's salt are another thermal storage
media. These materials are inexpensive, readilyavailable, and can deliver domestically useful
temperatures.
6) Solar energy can be stored at high
temperatures using molten salts. Salts are an
effective storage medium because they are low-
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cost, have a high specific heat capacity and can
deliver heat at temperatures compatible with
conventional power system.
Solar twos thermal storage system generated
electricity during cloudy weather and at night.
Beginning with the surge in
coal use which accompanied the Industrial
Revolution, energy consumption has steadilytransitioned from wood and biomass to fossil
fuels. The early development of solar
technologies starting in the 1860s was driven by
an expectation that coal would soon become
scarce. However development of solar
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technologies stagnated in the early 20th century
in the face of the increasing availability,
economy, and utility of coal and petroleum.
The 1973 oil embargo and
1979 energy crisis caused a reorganization of
energy policies around the world and brought
renewed attention to developing solar
technologies.
Dish Stirling systems of SBP in Spain.
Deployment strategies focused on incentive
programs such as the Federal Photovoltaic
Utilization Program in the US and the Sunshine
Program in Japan. Other efforts included the
formation of research facilities in the US (SERI,
now NREL), Japan (NEDO) and Germany
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(Fraunhofer Institute for Solar Energy Systems
ISE).
: The International
Organization for Standardization has established
a number of standards relating to solar energy
equipment. For example, ISO 9050 relates to
glass in building while ISO 10217 relates to the
materials used in solar water heaters.
Solar energy is of great use in
the development of human resources. With the
better use of solar energy, we can save it for our
next generation also. Solar energy is a clean,pollution free and renewable source of energy.
Development of this source of energy requires an
accurate detailed long-term knowledge of the
potential taking into account seasonal variations.
Its a good way to save on the electricity bill as
long as a backup generator is there in case the
energy supply from the battery runs out when
there is not much sun for a long period of time,
for example over winter.
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Solar energy can becollected using solar cells, mirrors, windows and
skylights and to just leave things out side to letthe sun heat them up. The energy can then be
converted into many different forms, for example
kinetic energy, light energy, heat energy and
sound energy.
My project on solar energy is
made with the help of google site, Wikipedia,
using text book, my own knowledge and with the
help of my co-teachers who made it possible for
me to make this project easily. I am very thankful
to my teachers for their help in making my
project.